Automatic volume control for stringed musical instruments



Dec. 6, 1966 G. E. STOBAUGH 3,290,425

AUTOMATIC VOLUME CONTROL FOR STRINGED MUSICAL INSTRUMENTS Filed March 19, 1965 Sfn'nged convrol lnsfrumenf c 'f A mp llfler Graham E. Slobaugh NV ENTOR.

9 54 68 BY Q 3 3 MM EM United States Patent 3,290,425 AUTOMATIC VOLUME CONTROL FQR STRINGED MUSICAL INSTRUMENTS Graham E. Stobaugh, Rte. 3, Box 401B, Rocky Mount, N.C. Filed Mar. 19, I965, Ser. No. 441,045 16 Claims. (Cl. 84--1.16)

This invention relates to musical instruments and more particularly to stringed instruments associated with an electronic amplifier.

The present invention pertains to the volume control of the amplified output from a steel string guitar or the like. At the present time, musical instruments of the type to which the present invention relates, are provided with manual or pedal operated controls through which the output volume is changed. It is therefore a primary object of the present invention to automatically change the volume of the amplified output of stringed instruments in such a fashion as to improve the performance of the instrument as well as to free the players hands or feet for operation of other controls.

An additional object of the present invention in accordance with the foregoing object, is to provide an automatic volume control for stringed instruments through which the volume of the amplified output is reduced during the contact intervals between the pick and the instrument strings so that the full output of the amplifier is precisely limited to the periods when the instrument strings undergo free vibration A still further object of the present invention is to provide an automatic volume control for an amplifier utilizing a photoresistive element the resistance of which is changed by illumination from a discharge glow device such as a neon lamp. Ignition and extinction of the lamp is in turn controlled through a solid state switching circuit in order to more rapidly control the change in the output volume of the amplifier. Accordingly, the particular circuit control arrangement of the present invention is particularly suited for the puaposes of obtaining a smoother musical sound from the instrument with which it is associated.

These together with other objects and advantages which will become subsequently apparent reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to the like parts throughout, and in which:

FIGURE 1 is a perspective view of a musical instrument utilizing the automatic volume control of the present invention.

FIGURE 2 is a perspective view of the pick connector arrangement.

FIGURE 3 is a block diagram illustrating the arrangement of the present invention; and

FIGURE 4 is an electrical circuit diagram of the volume control circuit associated with the present invention.

Referring now to the drawings in detail, FIGURE 1 illustrates a musical instrument generally referred to by reference numeral 10 which is in the form of an electric Hawaiian guitar having a pair of finger boards 12 which mount steel strings 14 adapted to be plucked by the player so that the vibrations of the strings produce musical tones. In this type of instrument, the sounds produced by vibration of the strings are amplified by an electronic amplifier. Also, vibration of the stringsv is induced by engagement therewith with a pick held by the fingers of the player.

In accordance with the present invention, three picks,

. 16, I8 and 20, are respectively positioned on the thumb,

forefinger and indexfinger of the players handso that vibration is induced in each spring following a contact 3,290,425 Patented Dec. 6, 1966 interval of short duration between the string and at least one of the picks. As more clearly seen in FIGURE 2, flexible wires 22 electrically connect each pick to a connector 24 mounted on a wristband 25 adapted to encircle the wrist of the player. The connectors therefore electrically connect the picks through the electrical cable 28 to the automatic volume control unit generally re ferred to by reference numeral 30 adapted to be mounted in any suitable location on the instrument as shown for example in FIGURE 1. The control circuit unit 30 establishes a pickup connection between the stringed instrument and the amplifier 32 as diagrammed in FIGURE 3 so as to amplify the musical sounds produced by vibration of the strings 14. The control circuit unit may therefore be provided with a jack for receiving a plug-in device 34 as shown in FIGURE 1 through which the control unit is connected to the amplifier.

Referring now to FIGURE 4, it will be noted that the control unit circuit is provided with its own source of electrical energy in the form of battery 38, the negative terminal of which is adapted to be grounded when the plug-in device 34 to the amplifier is received within the three-conductor jack device 40. Thus, insertion of the plug-in device 34 not only completes the power circuit for the control unit by grounding the negative terminal of the battery but also establishes an electrical connection between the amplifier and the signal input line 42 adapted to be connected to the guitar through the pickup plug 44. Also connected to the amplifier through the jack 40, in parallel with the input line 42, is a volume changing control component generally referred to by reference nu meral 46.

The volume changing control component 46 includes a potentiometer 48 for regulating the voltage level in the input line 42- above ground. Accordingly, the potentiometer 48 is connected in series with a photo-resistive element 50 between ground and the input line 42 so that when the photo-resistive element is in a low resistance condition, the setting of the potentiometer 48 will establish the minimum amplification for the signal conducted through the input line 42. The photo-resistive element 50 may be in the form of a cadmium sulphide photocell positioned adjacent to a discharge glow device 52 so that when the device 52 illuminates the photocell 50', its resistance is reduced to a low value. The discharge glow device 52 may be in the form of a gas filled neon lamp adapted to be ignited when the oscillator circuit 54 is operating.

The oscillator circuit 54 includes a PNP-type transistor 56 having the base and collector circuits thereof inductively coup-led to each other through the primary winding sections 5'8 and 60 of a three winding transformer 62 having an adjustable carbon slug 64. When the oscillator circuit is oscillating, .an output will be produced in the secondary winding 66 of the transformer connected to the neon lamp 52. As oscillating output is produced therefore, as the transistor 56 is switched between its conductive and non-conductive states and toward this end, the inductive coupling 62 controls the voltages on the collector and base relative to the positive voltage supplied to the emitter through the bias resistor 68. Thus, the grounded capacitor 70 controls the voltage held on the emitter of the oscillator transistor 56 and is charged by the battery 38 through the voltage reducing resistor 72 to which the capacitor 70 is connected. The oscillator circuit however, is normally prevented from operating by supply of a positive cut-off volt-age to the base of transistor 56 connected in series with the winding section 58 of the transformer 62. Accordingly, the Winding section 58 is connected to a control circuit portion generally referred to by reference numeral 74 from which the cut-off voltage is derived.

The control portion of the circuit includes a storage 3 capacitor 76 connected to the battery 38 through a voltage dividing network including the charging resistor 78 and the voltage limiting resistor 80. Also connected between the voltage reducing resistor 72 and the charging resistor 78, is a second capacitor 82. It will therefore be apparent, that when the maximum charge is held on the capacitor 76, the minimum charge will be held on the capacitor 82 since the voltage on both sides thereof will then be under control of the capacitors 76 and 70. Thus, the winding section 58 of transformer 62 is connected by conductor 84 to one side of the capacitor 82 so that a positive cut-off voltage will be supplied to the oscillator circuit to prevent oscillation thereof when the capacitor 76 is in its charged condition. Oscillation of the oscillator circuit however, begins as soon as the capacitor '76 discharges so as to change the voltage supplied to the base circuit in a negative direction. When the voltage on the base of the oscillator transistor 56 becomes sufficiently negative relative to the positive voltage applied to the emitter, the transistor conducts in order to start oscillation. Discharge of the capacitor 76 is therefore controlled by an NPN type transistor 86, the collector of which is connected to the positive side of the capacitor 76. It will therefore be apparent, that when the transistor 86 is rendered conductive, it will establish a discharge path to ground from the capacitor 76. The transistor 86 is however, normally held in a non-conductive state by .a solid state switching arrangement under control of the finger mounted picks.

It will be noted from FIGURE 4, that forward bias for the control transistor 86 is supplied by the battery 38 through the voltage reducing resistor 72 and the bias resistor 88 connecting the battery to the base of the transistor 86. However, this forward bias voltage is not held on the base of the transistor 86 since the base is normally grounded by the switching transistor 90. The switching transistor is therefore normally held in a condugtive state by the forward bias voltage held on its base by the capacitor 92 which is charged by the battery 38 through the resistors 72 and 94. The base of the switching transistor 90 is also adapted to be substantially grounded through the contact jack 96 connecting the base to at least one of the picks. Accordingly, during each contact interval between a pick and a string of the instrument, the normally conductive transistor 90 will be cut off in order to switch on the control transistor 86 for the duration of the contact interval.

From the foregoing description, the construction, operation and use of the control unit of the present invention will be apparent. The solid state switching circuit including the transistors 90 and 86 will therefore be operative to rapidly switch the oscillator circuit 54 to its operating condition in order to instantaneously ignite the neon lamp 52 as well as to cause instantaneous extinction thereof at the end of the contact interval. In this manner, the voltage changing control component 46 is operated only during each contact interval in order to reduce the volume of the amplifier to its minimum value as set by the potentiometer 48. Thus, maximum output volume from the amplifier is limited to those periods during which musical tones are produced by the strings undergoing free vibration. A much smoother musical sound is thereby produced than is otherwise possible by use of manual volume controls. Thus, the automatic volume control of the present invention not only improves the performance of the instrument but also frees the players hands or feet from the volume control function.

The foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention as claimed.

What is claimed as new is as follows:

1. In combination with a musical instrument having a string adapted to be vibrated by intermittent engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, an automatic volume control unit comprising, volume changing means operatively connected to the amplifier for changing the output thereof from a maximum value to a reduced value, signal transferring means operatively connected to the volume changing means for reducing the output of the amplifier in response to a signal of short duration, and contact means responsive to engagement of the string for instantaneously developing said signal of short duration.

2. In combination with a musical instrument having a string adapted to be vibrated by intermittent engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, an automatic volume control unit comprising, volume changing means operatively connected to the amplifier for changin g the output thereof from a maximum value to a reduced value, signal transferring means operatively connected to the volume changing means for reducing the output of the amplifier in response to a signal of short duration, and contact means responsive to engagement of the string for instantaneously developing said signal during each interval of contact with the string, said volume changing means including, a volume controlling potentiometer connected to the amplifier, photo-sensitive means connected to the potentiometer for establishing a conductive path to reduce the output of said amplifier and discharge glow means connected to the signal transferring means for illuminating said photosensitive means to reduce the resistance of said conductive path.

3. The combination of claim 2 wherein said signal transferring means comprises, an oscillator circuit connected to said glow means for energization thereof when oscillating, a source of voltage connected to said oscillator circuit for supply of energy thereto, and control means operatively connected to said oscillator circuit for preventing oscillation thereof except during said intervals of contact.

4. The combination of claim 3' wherein said contact means comprises, a pick adapted to engage the string, and switch means electrically connecting said pick to the control means for rendering the oscillator circuit operative to energize the glow means.

5. The combination of claim 4 wherein said switch means comprises, a current control device connected to said control means for supply of current thereto, means connecting said source of voltage to the device for normally rendering the same conductive .and signal means coupling the pick to the device for rendering the same non-conductive during the interval of contact with the string.

6. The combination of claim 5 'wherein said control means comprises, a transistor connected to said switch means, means connecting the source of voltage to the transistor for holding the same non-conductive when the switch means is closed, and capacitive circuit means connecting said transistor to the oscillator circuit for supplyin-g cut-off voltage thereto when the transistor is nonconductive.

7. In combination with a musical instrument having a string adapted to be vibrated by intermittent engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, an automatic volume control unit comprising, volume changing means operatively connected to the amplifier for changing the output thereof from a maximum value to a reduced value, signal transferring means operatively connected to the volume changing means for reducing the output of the amplifier in response to a signal of short duration, and contact means responsive to engagement of the string for instantaneously developing said signal during each interval of contact with the string, said signal transferring means comprising, an oscillator circuit connected to said volume changing means for energization thereof when oscillating, a source of voltage connected to said oscillator circuit for supply of energy thereto, and control means operatively connected to said oscillator circuit for preventing oscillation thereof except during said intervals of contact.

8. The combination of claim 7 wherein said control means comprises, a transistor connected to said contact means, means connecting the source of voltage to the transistor for holding the same nonconductive, and capacitive circuit means connecting said transistor to the oscillator circuit for supplying cut-01f voltage thereto when the transistor is non-conductive.

9. The combination of claim 8 wherein said contact means comprises, a pick adapted to engage the string, and switch means electrically connecting said pick to the control means for rendering the oscillator circuit operative to energize the glow means.

10. The combination of claim 1 wherein said contact means comprises, a pick adapted to engage the string,

and switch means electrically connecting said pick to the signal transferring means for operating the volume changing means.

11. In combination with a musical instrument having a string adapted to be vibrated by intermittent engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, anautomatic volume control unit comprising, volume changing mean-s operatively connected to the amplifier for changing the output thereof from a maximum value to a reduced value, signal transferring means operatively connected to the volume changing means for reducing the output of the amplifier in response to a signal of short duration, and contact means responsive to engagement of the string for instantaneously developing said signal during each interval of contact with the string, said contact means comprising, a pick adapted to engage the string, and switch means electrically connecting said pick to the signal transferrin-g means for operating the volume changing means, said volume changing means including, a volume controlling potentiometer connected to the amplifier, photo-sensitive means connected to the potentiometer for establishing a conductive path to reduce the output of said amplifier and discharge glow means connected to the signal transferring means for illuminating said photo-sensitive means to reduce the resistance of said conductive path.

12. In combination with a musical instrument having a string adapted to be vibrated by intermittant engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, an automatic volume control unit comprising a volume changing circuit having a photosensitive element, a neon lamp operatively positioned adjacent the photosensitive element, a source of voltage, an oscillator circuit connecting said source of voltage to the neon lamp [for energization thereof, at least two storage capacitors, a voltage dividing network connecting said source of voltage to both of said capacitors for charging thereof, solid state switching means connected to one of the capacitors for changing the charge on both of said capacitors in different directions, means connecting the other of said capacitors to the oscillator circuit to prevent oscill i n reof when aid one capacitor is in a predetermined charge condition, a pick adapted to engage the string during a contact interval for producing vibration thereof, and means electrically connecting said pick to the solid state switching means for changing the charge on said one capacitor from said predetermined charge condition during the contact interval, whereby the neon lamp is instantaneously ignited and extinguished in order to rapidly reduce and restore the resistance of the photo-sensitive element controlling the volume of the amplifier.

13. The combination of claim 12 wherein said electrical connecting means comprises, a wrist band, a connector mounted on said wrist band, a conductor connecting the connector to the pick, and an electrical conduit connecting the connector to the solid state switching means.

14-. In combination with a musical instrument having a string adapted to be vibrated by intermittant engagement thereof and an amplifier for increasing the volume of the sound produced by said vibration of the string, an automatic volume control unit comprising, volume changing means operatively connected to the amplifier for changing the output thereof from a maximum 'value to a reduced value, an oscillator circuit connected to the volume changing means for operation thereof, a source of voltage connected to the oscillator circuit for ener-gization thereof, at least two storage capacitors, a voltage dividing network connecting said source of voltage to both of said capacitors for charging thereof, solid state switching means connected to one of the capacitors for changing the charge on both of said capacitors in different directions, means connecting the other of said capacitors to the oscillator circuit to prevent oscillation thereof when said one capacitor is in a predetermined charge condition and contact means connected to the solid state switching means for changing the charge on said one capacitor from said predetermined charge condition during each interval of con tact with the string.

15. The combination of claim 14 wherein said volume changing means includes, a volume controlling potentiometer connected to the amplifier, photo-sensitive means connected to the potentiometer for establishing a conductive path to reduce the output of said amplifier and discharge glow means connected to the oscillator circuit for illuminating said photo-sensitive means to reduce the resistance of said conductive path.

16. In combination with a musical instrument producing sound in response to vibration of a string induced by deformation thereof during a contact interval of short duration, an amplifier connected to thes instrument, volume control means connected to the amplifier for regulating gain thereof, and means connected to the volume control means for automatically reducing the gain of the amplifier only during said contact interval.

References Cited by the Examiner UNITED STATES PATENTS 2,953,052 9/1960 Newton 841.16 2,961,912 11/1960 Meola 84-1.l5 3,156,769 11/1964- Marko-witz 84-124 3,160,694 12/1964 Meinema 84-1.24-

ARTHUR GAUSS, Primary Examiner.

J. BUSCH, Assistant Examiner. 

1. IN COMBINATION WITH A MUSICAL INSTRUMENT HAVING A STRING ADAPTED TO BE VIBRATED BY INTERMITTENT ENGAGEMENT THEREOF AND AN AMPLIFIER FOR INCREASING THE VOLUME OF THE SOUND PRODUCED BY SAID VIBRATION OF THE STRING, AN AUTOMATIC VOLUME CONTROL UNIT COMPRISING, VOLUME CHANGING MEANS OPERATIVELY CONNECTED TO THE AMPLIFIER FOR CHANGING THE OUTPUT THEREOF FROM A MAXIMUM VALUE TO A REDUCED VALUE, SIGNAL TRANSFERRING MEANS OPERATIVELY CONNECTED TO THE VOLUME CHANGING MEANS FOR REDUCING THE OUTPUT OF THE AMPLIFIER IN RESPONSE TO A SIGNAL OF SHORT DURATION, AND CONTACT MEANS RESPONSIVE TO ENGAGEMENT OF THE STRING FOR INSTANTANEOUSLY DEVELOPING SAID SIGNAL OF SHORT DURATION. 